Field of the Invention
The invention relates generally to methods and systems for extinguishing fires, and more particularly to sprinklers of such systems.
Description of Related Art
Fire suppression systems have been used in the United States to protect warehouses and factories for many years. In a fire suppression system, a fire sprinkler is positioned near the ceiling of a room where hot “ceiling jets” spread radially outward from a fire plume. When the temperature at an individual sprinkler reaches a pre-determined value, a thermally responsive element in the sprinkler activates and permits the flow of water as a water jet through a duct toward a deflector. The deflector redirects the water jet into thin streams or “ligaments” that break up into droplets due to surface tension. The water droplets deliver water to the burning material, reduce the combustion rate, wet the surrounding material, reduce the flame spread rate, cool the surrounding air through evaporation and displace air with inert water vapor.
Fire suppression systems can comprise a water distribution piping system to which a plurality of spaced-apart fire sprinklers are connected. Fire suppression systems and methods of installation are described in detail in my U.S. Pat. No. 8,602,118 (issued Dec. 10, 2013) and U.S. Pat. No. 8,733,461 (issued May 27, 2014), the entire disclosures of which are hereby incorporated by reference and relied upon.
When fire sprinkler heads are located close to each other, the risk of “cold soldering” becomes a concern. Cold soldering occurs when one fire sprinkler disperses a fire suppressing or extinguishing substance that directly cools a nearby fire sprinkler and prevents the latter fire sprinkler from properly responding and activating. Prior art pendant-type sprinklers are held closed by a trigger in the form of either a heat-sensitive glass bulb or a two-part metal link held together with fusible alloy. The trigger applies pressure to a closure element which acts as a plug in the sprinkler nozzle to prevent water from flowing until the ambient temperature around the sprinkler reaches the design activation temperature of the individual sprinkler head. Sprinkler heads located in open structures (i.e., not adjacent a wall, ceiling or beam) are commonly oriented vertically overhead (either pointing up or pointing down) and are provided with a deflector positioned in the path of water spray from the nozzle. The deflector redirects the vertically-discharged water jet into thin streams or “ligaments” that spread out uniformly in all directions (i.e., in a 360° discharge pattern) above burning materials to reduce the combustion rate, wet the surrounding material, reduce the flame spread rate, cool the surrounding air through evaporation and displace combustion air with inert water vapor.
Side-discharge sprinklers are a special type of fire sprinkler used in applications immediately adjacent a wall or beam or other blocking structure, as shown in FIGS. 1 and 2, which are documented in U.S. Pat. No. 7,331,399, the entire disclosure of which is hereby incorporated by reference. Side-discharge sprinklers are typically mounted in a horizontal orientation, as contrasted with the more common types of sprinkler heads which are mounted vertically up or vertically down (pendant). A typical side-discharge sprinkler can discharge approximately the same flow rate of water as the standard vertical mount design, but the distribution pattern of the water from a side-discharge sprinkler is directional and dispersed over a region generally about 180° (as compared with 360° in a vertical mount sprinkler). That is, a side-discharge sprinkler can discharge the same amount of water over time as that of a standard vertical mount type, but will distribute the water over roughly half the area due to is half-circle discharge pattern. As a result, the density of water per unit area of ground is greater for a side-discharge sprinkler. In fire suppression sciences, it is widely understood that the more water per unit time that can be delivered to burning material, the greater the reduction of combustion rate, better wetting, and so forth.
Despite their ability to discharge a greater water density, side-discharge sprinklers cannot be used in open surround conditions (i.e., located in the middle space between two structural beams (or girders, trusses, etc.) due to their inherent directional discharge patterns. In open surround conditions, a 360° discharge pattern is almost always used. Furthermore, side-discharge sprinklers cannot be positioned near one another due to the aforementioned cold soldering problem.
There is a need in the fire suppression and extinguishment field to create an improved fire sprinkler system that delivers a maximum density of water per unit area of ground.